I'm getting two unresolved symbols nf_hooks and nf_hooks_slow when compiling ipsec as a module with my 2.4.18 kernel. This prevents the ipsec module from successfully loading in my system.

I went through the ipsec building steps very carefully, I believe. Is there an obvious mistake I've made in the kernel config regarding netfilter or ipsec? Or is there another "gotcha" which I have overlooked?
( I also have these same two unresolved symbols in the bridge module, but it still seems to work, which is why I suspect a netfilter issue, not ipsec.)

Here is some (the relevant parts) of my .config

#
# Networking options
#
CONFIG_PACKET=y
# CONFIG_PACKET_MMAP is not set
CONFIG_NETLINK_DEV=y
CONFIG_NETFILTER=y
# CONFIG_NETFILTER_DEBUG is not set
# CONFIG_FILTER is not set
CONFIG_UNIX=y
CONFIG_INET=y
CONFIG_IP_MULTICAST=y
CONFIG_IP_ADVANCED_ROUTER=y
CONFIG_IP_MULTIPLE_TABLES=y
# CONFIG_IP_ROUTE_FWMARK is not set
# CONFIG_IP_ROUTE_NAT is not set
# CONFIG_IP_ROUTE_MULTIPATH is not set
CONFIG_IP_ROUTE_TOS=y
# CONFIG_IP_ROUTE_VERBOSE is not set
# CONFIG_IP_ROUTE_LARGE_TABLES is not set
# CONFIG_IP_PNP is not set
# CONFIG_NET_IPIP is not set
# CONFIG_NET_IPGRE is not set
# CONFIG_IP_MROUTE is not set
# CONFIG_ARPD is not set
# CONFIG_INET_ECN is not set
CONFIG_SYN_COOKIES=y

#
# IP: Netfilter Configuration
#
CONFIG_IP_NF_CONNTRACK=y
CONFIG_IP_NF_FTP=y
CONFIG_IP_NF_IRC=y
# CONFIG_IP_NF_QUEUE is not set
CONFIG_IP_NF_IPTABLES=y
CONFIG_IP_NF_MATCH_LIMIT=y
CONFIG_IP_NF_MATCH_MAC=y
CONFIG_IP_NF_MATCH_MARK=y
CONFIG_IP_NF_MATCH_MULTIPORT=y
CONFIG_IP_NF_MATCH_TOS=y
CONFIG_IP_NF_MATCH_AH_ESP=y
CONFIG_IP_NF_MATCH_LENGTH=y
CONFIG_IP_NF_MATCH_TTL=y
CONFIG_IP_NF_MATCH_TCPMSS=y
CONFIG_IP_NF_MATCH_STATE=y
# CONFIG_IP_NF_MATCH_UNCLEAN is not set
# CONFIG_IP_NF_MATCH_OWNER is not set
CONFIG_IP_NF_FILTER=y
CONFIG_IP_NF_TARGET_REJECT=y
# CONFIG_IP_NF_TARGET_MIRROR is not set
CONFIG_IP_NF_NAT=y
CONFIG_IP_NF_NAT_NEEDED=y
CONFIG_IP_NF_TARGET_MASQUERADE=y
CONFIG_IP_NF_TARGET_REDIRECT=y
# CONFIG_IP_NF_NAT_SNMP_BASIC is not set
CONFIG_IP_NF_NAT_IRC=y
CONFIG_IP_NF_NAT_FTP=y
CONFIG_IP_NF_MANGLE=y
CONFIG_IP_NF_TARGET_TOS=y
CONFIG_IP_NF_TARGET_MARK=y
# CONFIG_IP_NF_TARGET_LOG is not set
# CONFIG_IP_NF_TARGET_ULOG is not set
CONFIG_IP_NF_TARGET_TCPMSS=y
# CONFIG_IPV6 is not set
# CONFIG_KHTTPD is not set
# CONFIG_ATM is not set
# CONFIG_VLAN_8021Q is not set

#
# CONFIG_IPX is not set
# CONFIG_ATALK is not set
# CONFIG_DECNET is not set
CONFIG_BRIDGE=m
# CONFIG_X25 is not set
# CONFIG_LAPB is not set
# CONFIG_LLC is not set
# CONFIG_NET_DIVERT is not set
# CONFIG_ECONET is not set
# CONFIG_WAN_ROUTER is not set
# CONFIG_NET_FASTROUTE is not set
# CONFIG_NET_HW_FLOWCONTROL is not set


#
# IPSec options (FreeS/WAN)
#
CONFIG_IPSEC_IPIP=y
CONFIG_IPSEC_AH=y
CONFIG_IPSEC_AUTH_HMAC_MD5=y
CONFIG_IPSEC_AUTH_HMAC_SHA1=y
CONFIG_IPSEC_ESP=y
CONFIG_IPSEC_ENC_3DES=y
CONFIG_IPSEC_IPCOMP=y
CONFIG_IPSEC_DEBUG=y

Thanks for your help,

-Bob

OK, I found a way out. I turned off CONFIG_MODVERSIONS in my .config and recompiled. I guess bridge.o and ipsec.o don't support that.

Does no one else use either of these?